This invention relates to labels, and more particularly to polymeric film labels, and to a process of applying polymeric film labels to containers using a water-based adhesive.
It is common practice to apply labels to containers or bottles formed from polymers or glass. Such containers and bottles are available in a wide variety of shapes and sizes for holding many different types of materials such as detergents, chemicals, motor oil, soft drinks, alcoholic beverages, etc. The labels provide information containing the contents of the container and other information such as the supplier of the container or the contents of the container.
One widely used and well known labeling technique uses a water-based adhesive, and this technique is commonly known as water-based xe2x80x9ccold glue labelingxe2x80x9d or xe2x80x9cpatch labelingxe2x80x9d. In such labeling method, a water-based adhesive is applied to the label, which is usually held in a stack in a magazine, the label is then transferred to a transfer means, and the label is subsequently applied to the relevant container. The use of water-based adhesives requires that drying must take place by evaporation of the water. Accordingly, the early practice in this technology, which is still prevalent today, employed the use of labels manufactured from paper substrates which have a high vapor transmission rate xe2x80x9cWVTRxe2x80x9d so that drying of the adhesive after the label is applied to the container is not hindered. With paper labels, drying takes place in a few hours after application of the label to the container. The use of paper in conjunction with water-based adhesives, while providing for a quick drying label, results in other problems known in the industry such as poor tear resistance, moisture sensitivity, relatively poor durability, wrinkling, creasing, etc. Furthermore, it is becoming more common to recycle plastic and glass containers, and if a paper label has been utilized, it is not possible to recycle the container without removing the label prior to recycling.
Polymeric film materials and film facestocks have been described for use as labels in various fields, but their use in the labeling applications of the type discussed above in which a water-based adhesive is utilized has been limited because with polymeric films which are essentially non-permeable to water, it is very difficult for the moisture vapors to escape which is necessary for an accelerated drying process. The slow drying of the water-based adhesive when polymer films and facestocks are utilized in the labels also increases the time necessary to obtain a satisfactory bond of the label to the container. This often results in label movement during handling and storage, and visible bubbling effects at the surface of the label which are aesthetically undesirable. Bubbling has been observed to occur in particular at elevated temperatures such as exists in the summer.
Clear polymeric labels are increasingly desired, since they provide a no-label look to decorated glass and plastic containers. Paper labels block the visibility of the container and/or the contents in the container. Clear labels enhance the visual aesthetics of the container, and therefore the product, and are growing much faster than paper labels in the package decoration market as consumer product companies are continuously trying to upgrade the appearance of their products on store shelves.
Accordingly, it would be desirable to produce labels, in particular, polymeric film labels which can be applied to containers using a water-based adhesive wherein the adhesive dries and the label bonds to the container within an acceptable period of time.
In one embodiment, this invention relates to a label which comprises:
(A) a polymer facestock having an upper surface and a lower surface,
(B) a nano-porous layer having an upper surface and a lower surface wherein the upper surface of the nano-porous layer underlies the facestock, and the nano-porous layer contains pores having an average diameter of from about 1 to about 100 nm and the layer has a pore volume of from about 0.1 to about 2 ml./g., and
(C) a water-based adhesive in contact with the lower surface of the nano-porous layer.
In another embodiment, this invention relates to a label which comprises:
(A) a polymer facestock having an upper surface and a lower surface,
(B) a nano-porous layer having an upper surface and a lower surface wherein the upper surface of the nano-porous layer underlies the facestock, and the nano-porous layer contains pores having an average diameter of from about 1 to about 100 nm and has a pore volume of from about 0.1 to about 2 ml./g., and
(C) a metal layer overlying the upper surface of the facestock or underlying the facestock between the facestock and the nano-porous layer, said metal layer having an upper surface and a lower surface.
In addition, the present invention relates to a method of labeling substrates utilizing the above described labels and water-based adhesives.